title: Cytotoxic activity of benzo[b]cyclohept[e][1,4]oxazines.
abstract: BACKGROUND
  Although numerous articles have dealt with the biological activities of azulenes, studies of benzo[b]cyclohept[e][1,4]oxazines are limited. In the present study, we investigated a total of 14 newly-synthesized benzo[b]cyclohept[e][1,4]oxazines for their growth stimulation at low concentrations (so-called 'hormesis'), cytotoxicity at higher concentrations and apoptosis-inducing activity.
  
  
  METHODS
  Cytotoxicity of these compounds against human normal gingival fibroblast (HGF) and human oral squamous cell carcinoma cell lines derived from gingival tissue (Ca9-22), was evaluated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. The tumor specificity (TS) was determined by the ratio of the 50% cytotoxic concentration (CC₅₀) value for HGF cells to that for Ca9-22 cells. Apoptosis induction was evaluated by DNA fragmentation and caspase-3 activation.
  
  
  RESULTS
  Compounds 10-(2-methoxyethylamino)benzo[b] cyclohept[e][1,4]oxazine and 10-(3-methoxypropylamino) benzo[b]cyclohept[e][1,4] oxazine, but not other compounds, induced hormesis only in HGF cells. Compound 10-(6-hydroxyhexylamino)benzo[b] cyclohept[e][1,4]oxazine [4] showed the highest cytotoxicity against Ca9-22 cells, followed by 10-(4-hydroxybutylamino) benzo[b]cyclohept[e] [1,4]oxazine and 10-(5-hydroxypentylamino)benzo[b]cyclo-hept[e][1,4]oxazine. Compound [4] did not induce apoptosis markers, but rather induced necrotic cell death (characterized by a smear pattern of DNA fragmentation).
  
  
  CONCLUSIONS
  The present study suggests that the OH group and a certain length of methylene group are necessary for maximal cytotoxicity, and substitution of fluoride in the benzene ring enhances cytotoxicity.
authors.affiliation: Faculty of Science, Josai University, Sakado, Saitama, Japan.
authors.forename: Masanori
authors.initials: M
authors.lastname: Ohno
authors.forename: Jun-Ichi
authors.initials: J
authors.lastname: Ueki
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sakagami
authors.forename: Hidetsugu
authors.initials: H
authors.lastname: Wakabayashi
mesh_terms: D000970:Antineoplastic Agents / Q000737:chemistry / Q000494:pharmacology / Q000633:toxicity; D053148:Caspase 3 / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D002460:Cell Line; D002648:Child; D053938:DNA Fragmentation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D059165:Hormesis / Q000187:drug effects; D006801:Humans; D010078:Oxazines / Q000737:chemistry / Q000494:pharmacology* / Q000633:toxicity
chemical_list: D000970:Antineoplastic Agents; D010078:Oxazines; D053148:Caspase 3
keywords: Benzocycloheptoxazines; cytotoxicity; hormesis